The present invention relates to temperature sensors, particularly to high temperature probes for sampling gases for analysis, and more particularly to probe for sampling high temperature stack emissions, such as smokestack fumes.
The Environmental Protection Agency (EPA) requires the monitoring of smoke stack emissions. The monitoring and analysis of smokestack effluent generally utilizes probes inserted at various locations and depths in the smokestack. The effluent passing through the smokestack may have temperatures of several thousand degrees Fahrenheit (F.).
The temperature and/or effluent sensing and/or analysis systems have utilized water cooled probes which are inserted into the smokestack at selected locations and at various depths. The prior known probes utilize pressure differential devices, such as Pitot tubes, and a nozzle to draw a sample from the smokestack for analysis and/or measurement. In certain of the prior known probes, the nozzle draws the sample through a quartz liner in the water jacket connected to a device which collects the sample. These prior art probes use a Teflon seal between the metallic sampling nozzle and the end of the quartz liner located at the end of the water jacket adjacent the stack. Due to the closeness of the seals to the stack, they are exposed to high temperatures which causes degradation of the seal components and eventual leakage of the effluent being sampled.
The EPA requires that after the probe completes sampling of a smokestack effluent, the nozzle be sealed and a vacuum applied to the probe to test for air leaks, as leaks would create errors in measuring and/or analysis or the sample, and such is unacceptable to the EPA. It has been determined that the major cause of the leaks in the sampling probes was the seal which would decay at high temperatures.
Thus, there is a need in the art of sampling and monitoring of smokestack effluent, for example, or other high temperature fluids, for a probe which is not subject to leakage caused by degradation of components due to high temperatures of fluids being sampled by the probe. The present invention provides an effluent sampling probe that will not develop leaks due to high temperature degradation of components, such as a seal, can be moved to different regions of effluent flow, and thus meets EPA standards.